A Rutland police officer who was placed on administrative leave in December for an undisclosed “altercation” that was investigated by the state attorney general’s office has retired.

No criminal charges were ever brought against Thomas Fuller, a 26-year veteran of the force.

“There exists insufficient evidence to prove guilt beyond a reasonable doubt,” Cindy Maguire, the head of the attorney general’s criminal division, said in March.

While the criminal investigation involving an incident at Rutland Regional Medical Center ended months ago, Fuller did not return to work.

Rutland Police Chief James Baker said in March that Fuller remained on paid administrative leave due to an internal investigation that was being conducted at the department.

The altercation has never been described in detail. Hospital officials have said the incident did not involve a patient or staff member at RRMC. Fuller was on duty when the incident took place.

On Friday, Baker said Fuller’s retirement, which took place earlier this month, brought an end to the internal review.

“He chose to retire. Anything that was pending is a closed matter,” the chief said.

But Fuller said Friday he didn’t want to retire.

“I did not retire willingly,” he said. “However, I chose to step aside to further explore my options to address the issues that the department has presented me.”

Fuller also said he had a lack of faith in the leadership and their ability to deal fairly with officers — assertions that echoed concerns raised by another former city officer, Andrew Todd, who recently wrote to the police chief in Barre to complain about progress with an investigation into the Rutland department.

“The department’s ability to do a fair and impartial investigation into any matter regarding personnel is questionable as is the integrity of the people in charge,” Fuller said.

“Until people come forward and address the atmosphere of fear and speak their minds about what’s going on there, nothing will change,” he added.

Fuller isn’t the only city officer to retire recently following a criminal investigation by the attorney general’s office that resulted in no criminal charges.

In June, former officer Joseph “Michael” Warfle retired after 29 years with the force.

Warfle was placed on paid administrative leave after an investigation by the attorney general’s office began into unspecified issues related to his receipt of worker’s compensation benefits.

That investigation ended at the end of August with the decision not to bring charges.